Signal input device



FIG. 1 is a top, front and right-side perspective view of a signal input device showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof. 

The ornamental design for a signal input device, as shown. 